Adjustable quench pyrolysis furnace



Nov. 23, 1965 F. F. A. BRACONIER ETAL 3,219,419

ADJUSTABLE QUENCH- PYROLYSIS FURNACE Filed Oct. 25, 1960 :5 Sheets-Sheet 1 BY Cuah's,mmis Snflond ATTORNEYS.

' N 1965 F. F. A. BRACONIER ETAL 3,219,419

ADJUSTABLE QUENCH PYROLYSIS FURNACE 3 Sheets-Sheet 3 Filed Oct. 25, 1960 United States Patent 3,219,419 ADJUSTABLE QUEN CH PYROLYSIS FURNACE Frdric Francois Albert Braconier, 236 Rue de Strivay,

Plainevaux, Belgium, and Jean Joseph Lambert Eugene Riga, 9 Rue de Chaudfontaine, Liege, Belgium Filed Oct. 25, 1960, Ser. No. 64,962 Claims priority, application Austria, June 7, 1957, A 3,780/57 6 Claims. (Cl. 23277) This invention relates to a process and apparatus for treating hydrocarbons in the thermal decomposition thereof into less saturated hydrocarbons, and is particularly applicable for quenching the hot reaction gases in the thermal decomposition of hydrocarbon for the production of acetylene and/or olefines. This application is a continuation-in-part of our copending applications Serial No. 739,553, filed June 3, 1958, now Patent No. 2,978,521, and Serial No. 785,290, filed January 6, 1959, now abandoned.

To prepare acetylene and/or olefines from hydrocarbons such as methane, natural gas, gasolines, and hydrocarbon oils, the hydrocarbons are heated, in the gaseous or vaporized state, at an elevated temperature of between 1100 and 1500 C. or more, either by partial combustion of the hydrocarbon with oxygen or air, or by injecting the hydrocarbon into the hot gases, e.g., resulting from the combustion of oxygen and hydrogen, or oxygen and hydrogen-rich fuel.

In order to obtain high yields of unsaturated hydrocarbons, it is important to control the pyrolysis time of the hydrocarbon decomposition and to maintain it within narrow limits, since, at the necessary high temperatures, the pyrolysis reactions are not equilibrium reactions, but proceed as a function of the time with a consequential degradation of the unsaturated hydrocarbons formed in the first phase. For instance, when pyrolyzing hydrocarbons into acetylene by partial combustion, the reaction of pyrolysis time must be between 0.001 and 0.005 sec. The time of this reaction is ordinarily very brief, although it may vary somewhat depending upon the nature of the hydrocarbon to be pyrolyzed and the characteristics of the reaction chamber. It has been shown, for example, that when pyrolyzing methane, the yield of ethylene was almost doubled by reducing the reaction time from 0.014 to 0.0023 sec., at 1400 C., and the yield of acetylene increased about 8% with a pyrolysis time of 0.0029 sec. instead of 0.0085 sec. (cf. English Patent No. 709,035). At these higher temperatures, the pyrolysis reaction tends to proceed beyond the formation of the desired unsaturated hydrocarbons, with resulting production of carbon, hydrogen, etc.

The pyrolysis time is limited by quenching the gases obtained down to a temperature as low as 500 to 600 C., at which time the desired unsaturated hydrocarbons are more stable, as by transversely injecting into the gases a stream of cold water.

Although numerous processes have been proposed for quenching the hot pyrolysis gases, and although transversely spraying cold water into the gases may be the most economical method, this is not always satisfactory on an industrial scale. For example, if the quenching water penetrates into the pyrolysis zone, some of the evolving gases are prematurely cooled and the yield of unsaturated hydrocarbons thereby reduced. Thus, with a radial sprayer positioned axially at the end of the pyrolysis chamber, the projected water hits the wall of the pyrolysis chamber and splashes back in all directions. The kinetic energy of this water sufficient to cause splashing is used to prevent serious deviation of the water jets by the gaseous stream.

3,219,419 ?atented Nov. 23, 1965 Another problem is encountered when jets from the periphery of the pyrolysis zone are used. These meet counter-current in a central area, where they tend to create eddies, by which a portion of the quenching liquid is drawn back into the pyrolysis zone in a pattern which may vary from a water cone to a mist of droplets depending upon whether the quenched spraying is directed transversely or on slightly inclined directions with respect to the flow direction of the gaseous stream.

With previous devices, such eddies have been experienced even when said central spray is combined with the introduction of water through perforations situated along the wall of the pyrolysis zone or with a trickling of water therealong at the end of said zone.

In addition to the disclosure of this application, a pyrolysis furnace or reactor generally of the character to which this invention relates is also described in our co pending application, Serial No'. 432,216, filed May 25, 1954, now abandoned, of which our application Serial No. 785,290 is a continuation-in-part. That application is further concerned with a liquid dynamic screen to fully surround the sides of the reaction space and thus protect the walls of the furnace from carbon deposition and excessive heat. In both the screen and/ or the quench a variety of liquids including both water and oil may be used.

According to one aspect of the present invention, the various shortcomings mentioned above are overcome by a simple and original process and device, providing across the flow of hot gases a full transverse sheet of water which is kept entirely beyond a clearly defined, two-dimensional boundary. A first Water layer is formed by jets directed toward the longitudinal axis of the pyrolysis zone, originating from sprayers peripherally situated at the end of said pyrolysis zone; and advantageously, a second layer covers the first layer.

Also, according to further features of this invention, there is provided a pyrolysis chamber for the thermal treatment of hydrocarbons in which the position of the quenching jets is moveable along the furnace, whereby the axial positioning of the quenching jets or sprays is adjustable for controlling the time of the pyrolysis reaction and to permit quenching the hot gases at the particular moment of optimum yield from the reaction.

According to this invention, it is advantageous that the water sprayers should conform to the following when using a vertical furnace provided with a circular pyrolysis chamber.

(1) Slit openings for spraying water in blades towards the axis of the reaction zone, each blade having a spread of about 60.

(2) A truncated conical wall around the quenching zone and having a diameter greater than that of the pyrolysis chamber.

(3) An inclination of said conical wall of 10 to 15 with respect to the axis of the pyrolysis and quenching chambers.

(4) Positioning of the sprayers to give a twist inclination of each blade on an angle from 2 to 5 with respect to the horizontal plane.

When, respecting these conditions, the water jets originating from each sprayer under pressure, are arranged like the blades of a fan, overlapping horizontally they give a full and stable water layer, which extends slightly conically downward from the wall. From this water layer, emerges, at the bottom, a water cone formed by the juncture of the several blades and, at the head of the cone, a very light mist of water droplets forms which has substantially no detrimental efiect on the pyrolysis reaction.

These results are further improved if the first said water layer is covered with a second layer which prevents formation of the mist by an effect similar to a shearing. This second layer may originate most advantageously from the water screen which surrounds the reaction zone and protects the internal face of the wall of the pyrolysis chamber against carbon deposits (e.g., as described in the copending application, Serial No. 715,404, filed February 14, 1958, now Patent No. 3,073,875).

The accompanying drawings illustrate this invention by its use for the partial combustion of hydrocarbons into acetylene.

FIG. 1 is a diagrammatic representation, in vertical axial section, of a furnace for carrying out said partial combustion, the figure being broken away below the quenching zone of the apparatus.

FIG. 2 is a development of a portion of the truncated conical ring which forms the Wall of the quenching zone with the sprayers disposed therein.

FIG. 3 is a diagrammatic representation of a cross section through the furnace of FIG. 1, on the line X-Y, with three sprayers shown in only a 45 sector. These are representative of a greater number uniformly spaced about the wall of th furnace, but omitted to avoid merely repetitive showing.

FIG. 4 shows a partial vertical section of an annular furnace including the feature of this invention for adjusting the height of the quenching stream.

FIG. 5 is an transverse section of the furnace shown in FIG. 4.

FIG. 6 is a partial vertical section of an annular pyrolysis furnace showing the injection of the hydro carbons into hot gases which cause the decomposition of the hydrocarbon.

Referring, first, to the embodiment illustrated in FIGS. 1-3, the furnace shown is of the type represented by the one more fully described in the prior application, Serial No. 664,400, filed June 7, 1957, now Patent No. 2,970,178. It is provided with a distributor 1 having the form of a cylindrical refractory disc traversed by parallel passages 2 for distributing the reaction gaseous mixture into the combustion chamber within, and delimited by, an inner wall 4 'of the double-walled chamber. On its outer periphery, the distributor 1 is provided with a hollow metallic ring 5, having in it bottom an annular slit opening 6.

The inner wall 4 terminates at the bottom end of the combustion chamber. Below it, the outer wall 8 is flared to form a truncated conical ring 8 having a mean diameter greater than that of the combustion zone and inclined on an angle of with respect to the axis of the pyrolysis furnace. Sprayers 7 are disposed around the periphery of this conical ring 8. As indicated in FIG. 2, the injection orifice slits 7 of these sprayers are slightly inclined, advantageously on an angle of 2, with respect to the horizontal (normal) plane.

The preheated mixture of hydrocarbon and oxygen is introduced into the combustion zone 3 where it is ignited, through passages 2, from the usual mixing chamber or other reactant supply device. pressure through the hollow metallic ring 5 and ejected through the slit 6, along the wall 4 of the combustion chamber. Water is supplied through suitable piping to the sprayers 7 under sufficient pressure so that it fans out from the slit-orifices 7 in the form of thin blades having a 60 angle of spread, and slightly inclined downward, i.e., in the direction 'of the flow of the pyrolysis gases.

The sprayers 7 are spaced around the ring 8 to assure that th water blades overlap as indicated in FIG. 3, thus forming a full and homogeneous layer of the coolant at least co-extensive with the cross section of the pyrolysis zone, as represented in FIG. 3.

Water, supplied to the annular chamber 5 through pipe 5, passes out through slit 6 to form a liquid screen protecting the wall 4 against heat and/or carbon deposits.

Water is injected under This water runs down onto said first layer, by which it is picked up and carried across the chamber, thereby obtaining a stable and fully eflicient sheet resulting from said both layers and having a substantially uniform upper surface. The water in said sheet is, of course, moving transversely of the gas fiow and at such velocity that its path is little affected by the gas flow and gravity. The gas flows on through the interstices between the water but is impelled by it toward the center, so that ther is a greater exit velocity of the gas near the center, which aids the carrying off of any splash formed by impinging 'of opposed blades in the control area. To the extent that the water goes on to impinge on the opposite wall 8, it is below the jets from sprayers 7, so that splash does not get back into the pyrolysis zone.

In one example of using this process for quenching pyrolysis gases, a pyrolysis gas having an acetylen content of 8.4% (calculated on dry gas) was obtained by partial combustion of methane, While with previous quenching processes and apparatus, this content was only 8%.

Referring now to the embodiments illustrated in FIGS. 46, the pyrolysis chamber there shown has two parts, the first of which is a continuation of the second, said parts being moveable relative to one another axially of the chamber, i.e., in a telescopic arrangement, and wherein means for transversely injecting coolant into the stream of gases at the end of the pyrolysis zone is connected to one of said parts, the arrangement being such that, by moving one of said parts relative to the other, the length of the combustion chamber between the entry thereto and the location where the gases are quenched can be varied to vary time of pyrolysis. The pyrolysis chamber is generally circular and vertical, and the first part thereof is made as a sleeve fitting over the second part, the sleeve being mounted for vertical movement relative to the second part. The furnace of the invention most advantageously utilized a moving screen of liquid formed along th internal Wall of the reaction chamber to protect it from carbon deposits formed during the reaction, eg, of the type set forth in our copending application Serial No. 432,216 filed May 25, 1954. The moving screen of liquid form a hydraulic joint between the two parts of the combustion chamber, thereby serving to prevent loss of pyrolysis gases.

The provision in a pyrolysis furnace of a pyrolysis chamber the length of which is adjustable is particularly advantageous when a hydraulic joint between the sleeve and th pyrolysis member is maintained to prevent loss of pyrolysis gases, and especially when a moving screen of liquid is formed along the wall of the chamber, either internally to protect it from carbon deposit formed during the reaction, or externally to protect it thermally, the screen of water serving to form such a seal.

Thus, with the furnace just outlined, it is possible to vary the effective length of the pyrolysis chamber, so that the reaction time for pyrolysis can b varied to the optimum value for the particular hydrocarbon. It is thus possible by varying the length of the pyrolysis chamber to pyrolyse different hydrocarbons which require different pyrolysis times, and the conversion of the furnace from one set of operating conditions with one particular hydrocarbon to another set of operating conditions with another hydrocarbon can be easily effected, which was not possible With the previously known furnaces.

It has also been discovered that the water used for quenching and for forming the moving screen can be replaced With other liquids, such as oils which are not inflammable at the temperatures occurring in the pyrolysis reaction chamber. Accordingly, one aspect of the present invention provides a process for the pyrolysis of hydrocarbons (either by commingling the hydrocarbons to hot combustion gases, or by partial combustion of the hydrocarbons) wherein the gaseous reaction products are quenched by introducing into the gaseous reaction products oil which is not inflammable on the wall of the pyrolysis chamber during the pyrolysis reaction.

According to another aspect of the present invention, there is provided a process for the pyrolysis of hydrocarbons (either by commingling the hydrocarbons with hot combustion gases, or by partial combustion of the hydrocarbons) and thereafter quenching the gaseous reaction products, wherein the reaction is conducted in a pyrolysis chamber on the interior walls of which is formed a moving screen of oil which is not inflammable on the wall of the pyrolysis chamber during the pyrolysis reaction.

The use of such oil to form the moving screen as in our copending application, Serial No. 432,216, filed May 25, 1954, is particularly advantageous in the furnace of the invention, as the oil, being more coherent than water, forms between the sleeve and the pyrolysis chamber a seal which is particularly gas-tight.

Furthermore, it has been discovered that quenching and forming the moving screen with oil produces a partial purification of the pyrolysis gases by substantially reducing the diacetylene and vinylacetylene contents thereof, since the diacetylene and vinylacetylene are partially absorbed by the oil whereas the acetylene is not substantially dissolved by the oil. Also, the oil serves to remove the major part of the hydrocarbons having more than four carbon atoms. Such an oil is a petroleum fraction techni cally known as gas oil and generally distinguished by a boiling point range of primarily from about 250 C. to about 350 C., although minor amounts of lower boiling components come off as low as about 175 C. Alternatively the gas oil may be modified by the addition of minor amounts of the higher boiling components of the kerosene fraction, e.g., those oils having a boiling point range of 175 to 250 C.

The process of the invention for the control of the reaction period may be applied to any reaction involving thermal decomposition of hydrocarbons, whether by partial combustion or by injection into superheated steam or into other hot gases, where the reaction time must be accurately limited and controlled.

For a given production of the pyrolysis furnace, an optimum adaptation is obtained by continually analyzing the pyrolysis gases and regulating the quenching position, and thereby the length of the reaction chamber, and consequently the pyrolysis time, so that the content of desired unsaturated hydrocarbons, as shown by such analysis of the gases formed, remains substantially constant and maximum.

It has been observed also that this process makes it possible to vary the unsaturated hydrocarbon production of the same pyrolysis furnace. Thus, to vary the produc tion capacity of a given furnace from 100 to 65%, it is suflicient merely to modify the throughput of the reagents and the length of the reaction chamber. This advantage of the process of this invention is particularly interesting on the industrial scale, where the same pyrolysis furnace is suitable to a production varying, e.g., from to 6.5 tons/day of acetylene, without any structural modification. When pyrolyzing hydrocarbons into acetylene and ethylene, this variation of the production rate does not entrain any modification of the acetylene/ethylene ratio in the gases produced.

The furnace represented in FIG. 4 comprises a cylindrical disc shaped distributor 11 in refractory steel and traversed by the parallel passage 12 distributing the gaseous reaction mixture of hydrocarbon and oxygen into the chamber 13 surrounded by the side wall 14 wherein partial combustion heats the gases to pyrolysis temperature. A hollow ring 15 surrounds the distributor 11 and distributes a liquid through a slit shaped opening 16 to form a flowing screen on the interior of the Wall 14.

The lower portion of the wall 14 is surrounded and extended by a sleeve 17 having an internal diameter slightly greater than the external diameter of the combustion chamber. Said sleeve 17 is provided with an annular flange 18 on which a peripheral header 19 is mounted, said header being connected by pipes 20 to an axial feed pipe 21 feeding the coolant. Twenty-four jets 22 are uniformly distributed around the header 19 and connected to the header on a circle of diameter greater than that of the sleeve 17. The jets 22 have ejection slits slightly inclined (e.g., on an angle of approximately 2) with respect to the horizontal.

Water is also injected through ring 15 and the slit 16 along the wall 14 to form a projecting dynamic liquid screen and designed to form thin fan-like jet streams, advantageously having a divergence angle of 60 so that the liquid jet streams overlap and form a full disc-like layer transversely across the chamber 13. The location of the jets on the header 19, which is concentric with sleeve 17, but on larger diameter, provides for complete overlap of the jets in the area defined by the inner surface of sleeve 17 or the liquid screen.

The arrangement is such that when the main supply pipe is moved up or down the header 19 and sleeve 17 are correspondingly moved. The concentricity between the upper part of the reaction chamber and the sleeve can be maintained by guides, e.g., metallic rods welded to the outside of said wall, the sleeve 17 sliding thereon.

The gas feed is through the conduit 30 above the dis tributor 11, and the liquid for the flowing screen is fed through the pipe 31 shown at the left.

The preheated mixture of hydrocarbons and oxygen is introduced through the conduit 30 and the passages 12 of distributor 11 into the reaction zone 13, where it is ignited. Partial combustion of the hydrocarbon occurs, bringing the temperature up into the pyrolysis range. The gaseous reaction products are then quenched by water sprayed transversely into the gas stream through the jets 22 and associated pipes above described.

The liquid layer of the protecting screen of the wall 14 is spread over the wall 14 and the sleeve 17 forming a hydraulic seal preventing the pyrolysis gases from escaping through the narrow annular space between the outer surface of the Wall 14 and the sleeve 17. This liquid screen, which protects the wall 14, and the quenching liquid, as previously indicated, can be water or fire-re sistant oil.

The speed of introduction of oxygen and the hydrocarbon to 'be pyrolyzed, and the length of the chamber between the distributor and the location where the gases are quenched by the water sprayed into them determine the reaction time for pyrolysis (which should ordinarily be between 0.001 and 0.005 second when acetylene is to be produced). By moving the sleeve and its associated quenching spray means up and down, the length of the pyrolysis chamber between the distributor and the location Where the gases are quenched, can be varied, to vary the pyrolysis time, so that an optimum time of pyrolysis can be obtained. Also, by this means the pyrolysis time can be varied to obtain an optimum pyrolysis time for each of a succession of particular hydrocarbons being pyrolyzed.

Although the provision of a pyrolysis chamber the length of which can be adjusted is here described with reference to a furnace in which the pyrolysis is effected by partial combustion of the hydrocarbon with oxygen, it is also applicable to a pyrolysis furnace in which the hydrocarbon is injected into the hot gases, e.g., resulting from the combustion of oxygen and hydrogen, or oxygen and a hydrogen-rich fuel.

In FIG. 6 is shown an apparatus of the type having a combination chamber adjacent to a pyrolysis furnace. The hydrocarbon is introduced into hot combustion gases flowing from the combustion chamber. This furnace comprises essentially a combustion chamber 23 with feed pipes 24 and 25 (represented schematically) feeding the fuel gas and oxygen (or other combustion-supporting gas). These pipes are directly connected to the top of combustion chamber 23. Steam is injected through pipes 29. At the intersection of combustion and reaction chambers 23 and 26, there is a ring 27 provided with injector openings 27'. The wall 14 of the reaction chamber 26 is protected thermally by an outer flow of cold water fed through pipe 28. The lower end of the reaction chamber 26 is provided with a movable device for quenching the hot gases, said device being identical to that represented in FIG. 4.

The water circulating along the outer surface of the wall 14 passes between said wall and the sleeve 17, to form a hydraulic joint.

When normally operating, hydrogen rich fuel gas and oxygen are introduced through pipes 24 and 25 in the chamber 23, where they undergo combustion. The bydrocarbon to be pyrolyzed is injected by the sprayers 27 into the hot combustion gases through the reaction chamber 26. The hydrocarbon is thus thoroughly mixed with the hot gases and undergoes thermal decomposition in the chamber 26. The pyrolysis gases are then cooled by the quenching water screen formed with jets coming from sprayers 22 distributed on the header 19.

It is also to be noted that the water flowing along the outer surface of the wall 14, fully covers then the internal surface of the lower end of the sleeve 17, protecting the latter against the carbon and other deposits.

In another embodiment, a protecting continuous water screen is formed along the internal surface of the wall 14 of the chamber 26, in the place of, or additionally to, the outer water circulation.

Example 1.Partz'al combustion of methane into acetylene A partial combustion furnace as represented in FIG. 4, comprises a reaction chamber 13 within the wall 14 of internal diameter 430 mm. and external diameter 444 mm. The wall 14 has a length of 250 mm. and is surrounded at its lower end with the sleeve 17 having an internal diameter of 448 mm. and a length of 200 mm. 48 jets 22 are uniformly distributed around, and connected to the circular header 19 having a diameter of 648 mm. The header 19 is connected by pipes 20 (e.g. 3 pipes uniformly distributed) to the central pipe 21 having a diameter of 80 mm. Pipes 20 may have a diameter of 25 mm.

The concentricity of the sleeve 17 and the wall 14 is maintained by 3 guides consisting of metallic wires having a diameter of 2 mm. welded to the lower portion of the external surface of the wall 14.

The different constitutive parts of this furnace are in chromium-molybdenum refractory steel, e.g., an A.I.S.I. steel of the type 321 (according to the Steel Products Manual, No. 24 of the American Iron and Steel Institute).

The pipe 21 in this case, as in the case of FIG. 4, may be axially moved to adjust the position of the quenching apparatus in the stream of pyrolysis gases. Thus, the length of the reaction chamber may vary between 250 and 350 mm.

2150 Nm /H. (cu. meters/hr. computed at normal temperature and pressure) of 97% pure methane, preheated to 650 C. and 1200 Nm /H. of 97% pure oxygen also preheated to 650 C. were introduced into said furnace. 2 Nm /H. of water injected through the slit 16 forming a protecting screen along the internal surface of the wall 14. Meanwhile 18 Nm /H. of water were injected through the jets 22 for quenching of the combustion gases.

At the beginning of the operation, the length of the reaction chamber was 300 mm. When the operation was running smoothly, the pipe 21 was progressively moved upwards and downwards, while continuously analyzing the reaction gases. The jet position is then fixed at the position of maximum acetylene yield. In one instance a maximum yield of 7.8% of acetylene (calculated on the dry pyrolysis gas) was obtained with a length of '305 mm.

The following table shows the variations of the acetylene content of the pyrolysis gas according to the length of the combustion chamber.

Length of the chamber, C H content,

From this table, it is seen that the length of the reaction chamber must be adjusted accurately to obtain and maintain the maximum acetylene content in the pyrolysis gas.

Example 2.Pyr0lysis of liquid hydrocarbons into acetylene and ethylene A pyrolysis furnace of the type represented in FIG. 6 was used. The combustion chamber 23 had a diameter of mm. and a height of 168 mm., said chamber being provided with pipes 24 and 25 feeding the oxygen and the hydrogen-rich fuel and pipes 29 for injecting steam. Said combustion chamber is of the type described in our Belgian Patent Application No. 37,981 and in our US. application Serial No. 739,605 filed June 3, 1958, now Patent No. 3,055,957. The reaction chamber 26 has an internal diameter of mm. and an external diameter of 166 mm. The side wall 14 has a length of 600 mm.

The sleeve 17 has a diameter of 170 mm., and the peripheral header 19 on flange 18 has a diameter of 370 mm. measured on the circle of the twenty-four uniformly spaced jets 22. The heater 19 carries the sleeve 17 and is supported by three pipes 20 on movable central pipe 21 which has a diameter of 80 mm. The wall 14 of the pyrolysis chamber 26 is of refractory bricks cooled externally by cold water flowing down from the gap 28'.

Through the pipe 24, 250 Nm /H. of 93.5% pure oxygen were introduced into the combustion chamber 23. Through pipe 25, 260 Nm /H. of coke oven gas were introduced. The average composition of gas mixture was:

Volume Percent Hydrogen 59.8 Methane 26.8 C hydrocarbons 2.1 Carbon dioxide 1.9 Carbon monoxide 5.8 Oxygen 0.2 Nitrogen 3.4

Upon entering the chamber 23, these gaseous reagents were rapidly ignited and the flames were surrounded with steam screens introduced through pipes 29 with a total yield of 500 kg./H., as furtherdescribed in our said copending application.

524 kg./H. of a naphtha, at a temperature of 580 C. at the inlet of the pyrolsis furnace, were injected into the hob combustion gas. The characteristics of said naphtha were as follows:

Initial boilingpoint 41 C.

End point 130 C. Aromatic hydrocarbons 10% by weight. Naphthenic hydrocarbons 10.5% by weight.

9 fied and the conversion rate of the naphtha was substantially reduced (50% instead of 52%).

However, by adjusting the length of the pyrolysis chamber 26 according to the new throughputs, i.e., by reducing said length from 880 mm. to 590 mm., not only the ethylene/acetylene ratio was reset to approximately 2, but also the conversion rate of the naphtha was raised to 51.5%.

What is claimed is:

1. In a pyrolysis furnace of the character described for thermal decomposition and pyrolysis of hydrocarbons into less saturated hydrocarbons with hot combustion gases therein, the combination which comprises an elongated reaction chamber, means for introducing said hydrocarbons to be pyrolyzed and said hot combustion gases into said chamber, means for flowing around the walls of said reaction chamber a substantially continuous moving curtain of non-flammable liquid axially along said chamber, means for injecting transversely of said chamber a substantially continuous quenching screen of non-flammable liquid across said chamber from the periphery toward the center thereof and across the flow of said hydrocarbons and said combustion gases for quenching and arresting said pyrolysis reaction, said reaction chamber being formed of two closely fitting axially telescoping portions with the lower thereof displaceable with respect to the upper portion and with said means for injecting said quenching screen across said chamber being carried by said lower displaceable telescoping portion, and means for displacing and adjusting the axial position of said lower telescoping portion and said quenching means thereon for adjusting and controlling the axial level of said transverse quenching screen for arresting said pyrolysis reaction at the axial level in said chamber where optimum production of said less saturated hydrocarbons occurs, said axially flowing curtain of liquid also forming a seal at the juncture between said telescoping portions for preventing escape of gases from said chamber through said juncture.

2. Apparatus as recited in claim 1 in which said transverse quenching screen of liquid is formed by a plurality of inwardly directed spray jet nozzles around said chamber for producing overlapping sprays of liquid which join in said chamber to form said transverse quenching screen of liquid.

3. Apparatus as recited in claim 1 which also includes means for separately introducing into said chamber said hydrocarbons to be pyrolyzed and said hot combustion gases for admixture and pyrolysis therein.

4. In apparatus for controlling a pyrolysis decomposition reaction of hydrocarbons into less saturated hydrocarbons in a cylindrical pyrolysis reaction chamber and for quenching hot pyrolysis gases to arrest said pyrolysis reaction at a predetermined level in said reaction chamber, the combination which comprises means for forming a substantially continuous screen of non-flammable liquid within said reaction chamber for enclosing said pyrolysis gases and flowing axially within said chamber in the same direction as the flow of said gases therein at least to said predetermined level for quenching said gases in said chamber, a plurality of radially inwardly directed non-flammmable liquid spray jet nozzles around said reaction chamber disposed on a transverse plane therethrough substantially at said predetermined quenching level axially thereof, said nozzles being disposed around said reaction chamber radially outside the periphery thereof defined by said axially flowing screen of liquid, means for mounting said plurality of nozzles in said apparatus for directing transversely overlapping sprays of liquid radially inwardly into said chamber and downwardly inclined therein at an angle of about 10-15 with respect to a transverse plane to said chamber normal to said flow of said gases therein, each of said plurality of radially inwardly directed jet nozzles having an outlet orifice having a narrow elongated transverse slot for producing said sprays of liquid in the form of a flat fan-like spray into said chamber, and with each of said orifice slots angularly inclined about the axis of said orifice and with respect to a transverse plane through said chamber whereby individual sprays of liquid from said orifice slot into said chamber overlap before liquid from one said spray directly impinges upon liquid from an adjacent said spray, the lower portion of said reaction chamber adjacent said nozzles being formed as an axially movable portion closely telescoping with the remainder of said chamber and carrying said nozzles, and means for adjusting the axial position of said closely telescoping portion and said nozzles for controlling and adjusting said predetermined quenching level.

5. Apparatus as recited in claim 4 in which the angle at which said orifice slots are inclined about said axis of said orifice is approximately 25 for effecting substantially complete overlapping of said fan-like sprays.

6. Apparatus a recited in claim 4 in which said spray orifice slots are configured to provide a substantially transverse spreading of said fan-like liquid sprays therefrom having an angle of about 60 at the radially outer apex of each spray effecting substantially complete overlapping of adjacent individual sprays from said orifices for forming a substantially continuous transverse layer of liquid therefrom around said chamber at least in the area thereof where said axially flowing screen of liquid impinges upon said transverse layer of liquid formed from said individual sprays.

References Cited by the Examiner UNITED STATES PATENTS 2,179,379 11/1939 Metzger 260679 2,371,147 3/1945 Burk 260679 2,416,227 2/1947 Seyfried 260679 2,439,730 4/ 1948 Happell 260679 2,680,706 6/ 1954 Kilpatrick 260-679 2,719,184 9/1955 Kosbahn et al. 260679 2,805,131 9/ 1957 Mclntire 260679 2,805,268 9/1957 Cunningham 260679 2,813,138 11/1957 MacQueen 260679 2,848,305 8/1958 Lehrer et al. 260679 2,868,856 1/1959 Hale et al. 260679 2,897,062 7/1959 Minarik 260679 2,905,731 9/1959 Seed 260679 2,978,521 4/1961 Braconier et al 260679 3,009,784 11/1961 Krejci 23209.4

OTHER REFERENCES Patton et al.: Petroleum Refiner, vol. 37, No. 11, pages -186, November 1958.

ALPHONSO D. SULLIVAN, Primary Examiner.

JOSEPH R. LIBERMAN, Examiner. 

1. IN A PYROLYSIS FURNACE OF THE CHARACTER DESCRIBED FOR THERMAL DECOMPOSITION AND PYROLYSIS OF HYDROCARBONS INTO LESS SATURATED HYDROCARBONS WITH HOT COMBUSTION GASES THEREIN, THE COMBINATION WHICH COMPRISES AN ELONGATED REACTION CHAMBER, MEANS FOR INTRODUCING SAID HYDROCARBONS TO BE PYROLYZED AND SAID HOT COMBUSTION GASES INTO SAID CHAMBER, MEANS FOR FLOWING AROUND THE WALLS OF SAID REACTION CHAMBER A SUBSTANTIALLY CONTINUOUS MOVING CURTAIN OF NON-FLAMMABLE LIQUID AXIALLY ALONG SAID CHAMBER, MEANS FOR INJECTING TRANSVERSELY OF SAID CHAMBER A SUBSTANTIALLY CONTINUOUS QUENCHING SCREEN OF NON-FLAMMABLE LIQUID ACROSS SAID CHAMBER FROM THE PERIPHERY TOWARD THE CENTER THEREOF AND ACROSS THE FLOW OF SAID HYDROCARBONS AND SAID COMBUSTION GASES FOR QUENCHING AND ARRESTING SAID PYROLYSIS REACTION, SAID REACTION CHAMBER BEING FORMED OF TWO CLOSELY FITTING AXIALLY TELESCOPING PORTIONS WITH THE LOWER THEREOF DISPLACEABLE WITH RESPECT TO THE UPPER PORTION AND WITH SAID MEANS FOR INJECTING SAID QUENCHING SCREEN ACROSS SAID CHAMBER BEING CARRIED BY SAID LOWER DISPLACEABLE TELESCOPING PORTION, AND MEANS FOR DISPLACING AND ADJUSTING THE AXIAL POSITION OF SAID LOWER TELESCOPING PORTION AND SAID QUENCHING MEANS THEREON FOR ADJUSTING AND CONTROLLING THE AXIAL LEVEL OF SAID TRANSVERSE QUENCHING SCREEN FOR ARRESTING SAID PYROLYSIS REACTION AT THE AXIAL LEVEL IN SAID CHAMBER WHERE OPTIMUM PRODUCTION OF SAID LESS SATURATED HYDROCARBONS OCCURS, SAID AXIALLY FLOWIWNG CURTAIN OF LIQUID ALSO FORMING A SEAL AT THE JUNCTURE BETWEEN SAID TELSCOPING PORTIONS FOR PREVENTING ESCAPE OF GASES FROM SAID CHAMBER THROUGH SAID JUNCTURE. 